OTC and hyperinsulinemic hypoglycemia, familial, 4: In a previous study (Soria et al, 2018), we showed that rapamycin reduces orotic acid in spf‐ash mice, a mouse model of the ornithine transcarbamylase (OTC) deficiency that carries a single nucleotide mutation in the fourth exon of the Otc gene resulting in a splicing defect and 10% of residual enzyme activity (Hodges & Rosenberg, 1989).